An investigation will be launched into whether a town was left underwater because a switch on an £8m flood defence scheme failed to work.
Homes and businesses in Horncastle and surrounding villages were inundated when the Rivers Bain and Wairing burst their banks following torrential rain on Friday.
The incident happened despite a flood alleviation scheme, which was completed in 2017.
The scheme, consisting of a flood storage reservoir on the River Bain, upstream of Horncastle, uses farmer John Harrison's land.
He said the damage could have been avoided.
"I know for a fact... the mechanism was not working," he said. "It was allowing all the water to flow down river towards Horncastle."
He said he contacted the Environment Agency about the issue and was told the agency was aware.
"I think it's horrendous," he said. "They spent £10m or so on it and one little item on it failed. They come and check the dam twice a year and, when this [weather] was announced three or four days before Storm Babet, they should have been there to make sure it worked.
"If I was a resident I would be putting in a big claim. The whole things is awful. Heads need to roll."
On Tuesday, Lincolnshire county councillors promised to investigate.
Updating the authority’s Economy and Environment Committee on Tuesday, Cllr Colin Davie said more than 600 individual flooding reports were under analysis.
"It was a very mega event on Friday," he said.
"The intensity of rainfall was biblical, but it’s not the first time we’ve had so much rain. We have a new pattern of weather that’s going to impact the way we need to do business in the future.
“There have been a lot of concerns around Horncastle in relation to what happened with the flood mitigation scheme there.
“Quite clearly something went wrong in Horncastle. The Louth [flood defences] worked and adequately protected that community.
“There needs to be a full review."
During the meeting, councillors said other defence schemes had been successful.
Cllr Alison Austin said Kirton had remained “bone dry”.
Cllr Ian Carrington added: “To all residents and businesses alike affected by the flooding, there is simply nothing more soul-destroying than a home or business being flooded out.
“We all know the amount of time it takes to recover from that. The message that I would like to put out from this committee is one of support and sympathy to all our residents who have been affected."
The Environment Agency said it would conduct its own review in due course.
A spokesperson said: "We are aware of concerns regarding the operation of the Horncastle Flood Alleviation Scheme.
“Our current priority remains emergency response working with the Lincolnshire Local Resilience Forum. We will review our incident response and asset operation once the incident abates and we move out of the emergency phase.”
“We know the devastating impact that flooding can have, which is why protecting people and communities is our top priority."
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